1. Field of the Invention
The invention relates generally to dental equipment and specifically to devices for evaluating the alignment of a dental patient's dentition. In another aspect, the invention relates to a device for aligning a dental patient's dental midline and facial midline or saggital plane. In another aspect, the invention relates to a device for establishing a level horizontal incisal plane. In yet another aspect, the invention relates to an adapter for incorporating a saggital plane alignment device and/or horizontal plane indicator with a conventional impression/bite tray. In yet another aspect, the invention relates to a device for determining the pitch axis of a patient's maxillary arch.
2. Description of the Related Art
A dentist may at times be presented with the necessity of performing restorative dentistry on a patient which implicates the anterior dentition. Such dentistry may be necessary due to injury involving a loss of teeth, or the need to move teeth as a part of orthodontic treatment, or cosmetic dentistry. To ensure that an optimal patient appearance is achieved, it is typically necessary to properly align or parallel the dental midline with the facial midline, also referred to as the saggital plane, or to establish a level horizontal plane for the incisal edges. This is particularly difficult when a patient's dental midline relative to the patient's facial midline is angularly displaced.
A prior art device for indicating the dental midline relative to the facial midline and incisal plane is illustrated in FIGS. 1A and 1B. A facial plane relator 10 comprises an arch 12 terminating radially outwardly in a generally flattened arch plate 14 coplanar therewith. The medial portion of the arch plate 14 transitions into a plane indicator support 16 which is adapted to support a horizontal plane indicator 18 and a vertical plane indicator 22 in orthogonal alignment. The plane indicators 18, 22 are rod-like members. The horizontal plane indicator 18 is illustrated as permanently attached to the plane indicator support 16 coplanar with the arch plate 14, although the horizontal plane indicator 18 can alternatively be adapted for selective removal from and installation to the plane indicator support 16. The vertical plane indicator 22 is illustrated as removably attached to the plane indicator support 16 by frictional or interference engagement with a cradle 20. Extending radially inwardly from the inner edge of the arch 12 is a plurality of regularly-spaced, generally rigid fingers 24.
Referring to FIG. 1B, the facial plane relator 10 is utilized by first applying a bite registration material onto the arch 12 and support fingers 24 of the facial plane relator 10. The facial plane relator 10 is then placed into the patient's mouth. When the patient bites down on the registration material, the material extrudes toward the lips. The facial plane relator 10 can be adjusted laterally and rotationally to properly align the vertical alignment bar 22 with the patient's facial midline. After the registration material has cured, the resulting impression with the facial plane relator 10 intact is removed from the patient's mouth. This is provided to a dental lab for preparation of a dental restoration which will have a dental midline which is properly aligned with the patient's facial midline.
The prior art facial plane relator suffers from several deficiencies. First, if the volume of registration material applied to the facial plane relator is insufficient; the facial plane relator may be inadequately supported leading to inadvertent separation of the facial plane relator from the registration material. Second, alignment of the facial plane relator with the patient's facial midline requires movement of the facial plane relator, and the fingers, in a thick, high viscosity material, which can be very difficult to adjust and hold in an exact position until the material is completely set. Third, the mass of registration material must be great enough on the tray so the patient bites into the material but not on the facial plane relator. If the patient bites the facial plane relator, it will eliminate the adjustment accuracy of the facial plane relator.